A light-emitting diode (LED) is a two-lead semiconductor pn-junction (diode) that also a emits light. When the anode lead of an LED has a voltage that is positive relative to the cathode of the LED by more than the LED's forward voltage drop, current flows through the LED. LEDs exhibit electroluminescence, which is an optical phenomenon and electrical phenomenon in which a material emits light in response to the passage of an electric current or to a strong electric field.
Generally, a resistor may be used to regulate current through an LED. However, this may waste power because as current flows through the resistor and the LED the resistor will generally dissipate some of the energy of the current flow as heat. In order to avoid some of the losses in the resistor, an LED may be powered by an LED driver. The LED driver may provide current to the LED using, for example, a switched mode power supply, such as a buck converter, or other power source.